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The simple and easy way to manufacture counter electrode for dye-sensitized solar cells
Jo-Lin Lan,Yung-Yun Wang,Chi-Chao Wan,Tzu-Chien Wei,Hsien-Ping Feng,Chao Peng,Hai-Peng Cheng,Ya-Huei Chang,Wen-Chi Hsu 한국물리학회 2010 Current Applied Physics Vol.10 No.2
We previously developed poly-N-vinyl-2-pyrrolidone (PVP)-capped Pt nanoclusters on ITO glass via a simple ‘‘2-step dip coating process” as counter electrode for DSSC. This new counter electrode was examined by transmission electron microscopy (TEM), inductively coupled plasma-atomic emission spectroscopy (ICP-AES), electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and current–voltage curve (I–V curve). The TEM results revealed that PVP-capped Pt nanoclusters’ size is about 3 nm, and the amount of Pt deposited on ITO glass is about 5 ㎍/㎠. Comparing with sputtered Pt and Solaronix thermal cluster Pt-catalyst T/SP, the PVP-capped Pt counter electrode has lower amount of Pt deposited on TCO glass,more positive potential of tri-iodide reduction, and better performance for the charge-transfer resistance (RCT) and the cell efficiency (g).
A Study on the Development of Rotary Ultrasonic Machining Spindle
Chang-Ping Li(이상평),Min-Yeop Kim(김민엽),Jong-Kweon Park(박종권),Tae-Jo Ko(고태조) 한국기계가공학회 2015 한국기계가공학회지 Vol.14 No.4
Ultrasonic machining (USM) has been considered a new, cutting-edge technology that presents no heating or electrochemical effects, with low surface damage and small residual stresses on brittle workpieces. However, nowadays, many researchers are paying careful attention to the disadvantages of USM, such as low productivity and tool wear. On the other hand, in this study, a high-performance rotary ultrasonic drilling (RUD) spindle is designed and assembled. In this system, the core technology is the design of an ultrasonic vibration horn for the spindle using finite element analysis (FEA). The maximum spindle speed of RUM is 9,600 rpm, and the highest harmonic displacement is 5.4 μm noted at the frequency of 40 ㎑. Through various drilling experiments on glass workpieces using a CVD diamond-coated drill, the cutting force and cracking of the hole entrance and exit side in the glass have been greatly reduced by this system.
Mechanism analysis of hybrid machining process comprising EDM and end milling
Li, Chang Ping,Kim, Min-Yeop,Islam, Md. Mofizul,Ko, Tae Jo Elsevier 2016 Journal of materials processing technology Vol.237 No.-
<P><B>Abstract</B></P> <P>STD 11 alloy steel is an extremely hard and difficult-to-cut material that is used extensively in cutter and die manufacturing for its superior wear resistance. This paper introduces a hybrid machining process (HMP) based on EDM and end milling (EDM-end milling) as an effective method for machining difficult materials. The HMP combines cutting action and an electrical thermal process. The machining mechanism was investigated, and a mathematical model of EDM-end milling is presented. Simulated and experimental cutting results were compared to validate the model. A tungsten carbide end mill was used as a tool electrode to machine STD 11 alloy steel (H<SUB>R</SUB>C 60) with different electric energy pulses. The results show that the method greatly improves tool wear and machining efficiency.</P>
Hao Tang,Chang Ping Li,Jia Chen,Huimin Kang,Tae Jo Ko,Mianke Du 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.10
In this paper, an optimized error sensitivity analysis (ESA) approach based on stream-of-variation (SOV) theory in multi-axis precise motion platform (MPMP) is introduced. Unlike the conventional ESA method, this approach utilizes stream-of-variation theory to establish error model firstly. By regarding each axis as a station, the error propagation and deviation accumulation processes are clear station by station. Through obtaining the deviations after each station, the sensitive stations can be developed, and corresponding error terms are collected. Thus, by analyzing the appearance frequency of the errors, a precise sensitive order can be developed, and a sensitivity results with different steps is given. Through ignoring the insensitive and irrelevant errors, the computational volume of error model can be saved, and the efficiency can be improved. A case study about a typical MPMP used in laser welding system (LWS) is carried out, and the results indicate that the optimized ESA approach is more efficient and accurate, and it is flexible as well. This ESA approach is not only accurate in developing sensitive levels, but also balancing the systematic accuracy and working efficiency, which is helpful to provide informative guide to engineers.
Lu-Yen Chen,Jo-Ming Tseng,Chung-Hwei Su,Kuen-Yuan Chuang,Chun-Ping Lin,Shuh-Woei Yu 한국화학공학회 2012 Korean Journal of Chemical Engineering Vol.29 No.10
Tert-butyl(2-ethylhexyl)monoperoxy carbonate (TBEHC) 95 mass% is intrinsically a very unstable substance that can induce self-decomposition even under normal atmospheric condition. During storage, TBEHC 95mass%can release an enormous amount of heat if the temperature is higher than the recommended storage temperature, due to the self-accelerating reaction having been ignited. In this study, TBEHC 95mass% was tested by differential scanning calorimetry (DSC) under five heating rates (1, 2, 4, 6, and 8 oC/min) and four isothermal conditions (120, 125, 130,and 135 oC) to evaluate the basic kinetic and safety parameters of time to maximum rate (TMR), self-accelerating decomposition temperature (SADT), and temperature of no return (TNR). Under runaway reaction TBEHC 95 mass%releases a great quantity of heat. This study establishes an important guiding principle for related manufacturing processes worldwide.
원성재(Sung-Jae Won),이상평(Ching-Ping Li),박기문(Ki-Moon Park),고태조(Tae Jo Ko) 한국기계가공학회 2017 한국기계가공학회지 Vol.16 No.1
CFRP has many industrial applications due to its low weight and high strength properties. CFRP is a composite material composed of carbon fibers embedded in a polymer matrix; it provides excellent resistance to fatigue wear, corrosion, and breakage due to fatigue. It is increasingly demanded in aircraft, automotive, and medical industries due to its superior properties to aluminum alloys, which were once considered the most suitable for specific applications. The basic machining methods of CFRP are drilling and route milling. However, in the case of drilling, the delamination of each layer, uncut fiber, resin burning, spalling, and exit burrs are barriers to successful application. This paper investigates the occurrence of exit burrs when drilling holes with ultrasonic vibration. Depending on design parameters such as the point angle, the characteristics of hole drilling were identified and appropriate machining conditions were considered.